Cutting wrapping film on a lap seal machine

ABSTRACT

In a lap seal machine there is a need to provide a predetermined length of film for wrapping a product. This is accomplished by cutting a predetermined length of film while wrapping an article with the film. The wrapping is done by a fly bar that stops after a predetermined length is pulled. The stopped film is then cut by a knife.

FIELD OF INVENTION

This invention relates to cutting wrapping film to a predetermined length of film for wrapping an article on a Lap Seal machine. The cutting takes place after the fly bar begins film wrapping the product.

SUMMARY OF THE INVENTION

The objective of this invention is to replace the need for a shear and vacuum belt or separation rollers used in feeding a predetermined length of film in a lap seal machine. This is accomplished by cutting a predetermined length of film while wrapping an article with the film. The term article is used to define a single article or a bundle of articles. These changes result in substantial economic savings in the construction of the machine.

BACKGROUND OF THE INVENTION

FIG. 1 is a conventional lap seal machine. A roll of film 2 is usually provided with printed sections spaced apart so the film can be cut without having to cut through the printed sections. Film 1 is pulled of a roll 2 by film feed rollers 5 and is fed through a dancing roll 3. From the dancing roll 3 the film goes past a sensor 4. The sensor 4 detects the location of the print or a detectable mark on the film so that a shear 6 can cut the film to a predetermined length without cutting through the printed portion of the film. From the sensor 4 the film goes to a film feed rollers 5. Feed rollers 5 push the film through the shear 6 on to vacuum belt conveyor 7. Conveyor 7 moves the film so that a flap 10 of the film is on conveyor 9. The conveyor 7 stops and waits for the next cycle. During this time the shear cuts the film 1 to predetermine length. An article moves on top of the flap on conveyor 9. Afterward flybar 8 picks up the film from underneath the conveyor 9 to wrap the article as it moving on the conveyor with the predetermined length of film.

FIG. 2 is similar to FIG. 1 except the vacuum conveyor and the shear has been replaced by a separation rollers and a film that has perforations lines across the width of the film. This application incorporates by reference, in the entirety, U.S. Pat. No. 7,836,670, filed Nov. 23, 2010 by the same inventor which describes the invention shown in FIG. 2.

The separation rollers and the film feed rollers act to separate the film along the perforation line. The separation rollers 1 land feed mean rollers 5 are spaced as close possible. The film 1 is pulled off the roll 2 and a flap 10 of the film is pushed onto belt conveyor 7. While the film is being pulled off the roll 2, a conventional sensor as used in FIG. 1 can be used to detect the location of the perforation line. Usually the film is pre marked so that the sensor can detect the location of the perforation line. When the perforation line moves to a position between film feed rollers 4 and separation rollers 11, the film feed rollers slows down. The separation roller maintains its speed. This difference in speed of the rollers causes a force that mechanically separates the film along the perforation line at separation point 15. The feed rollers after the film separation continue to push the film between the separation rollers so a flap of the film rests on the transfer belt of a conveyor 9. The conveyor 9 transfers the article to another conveyor. The flybar 8 pulls the film into a slot between the conveyors causing the film to be overlapped when the product is transferred to the other conveyor.

BRIEF DESCRIPTION OF THE INVENTION

FIG. 1 shows film wrapping using a vacuum belt.

FIG. 2 shows using separation rollers to separate perforated film.

FIG. 3 shows a cutting knife positioned after the film feed rollers

FIG. 4 shows cutting a film to a predetermined length after stopping the film.

FIG. 5 shows overlapping the film by transferring that article to another conveyor.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 3 shows a film 1 pulled from film roll 2 by film feedrollers 5. The film feed rollers 5 pushes the film so a flap 10 rest on a first conveyor 9 that transfers the article to a second conveyor 19. Usually the second conveyor 18 is a heat shrink conveyor that transfers the article through a heat shrink tunnel.

After the flap 10 is placed on conveyor 9, flight bar conveyor 19 pushes the article 14 onto flap 10. FIG. 4 shows fly bar 8 picking up the film from behind the product and over the top of the product. Fly bar 8 and feed rollers 5 pull the film to a predetermined length sufficient to wrap the article. After the predetermined length has been pulled, the feed rollers 5, flybar 8 and conveyor 9 stop. This causes the film to stop moving. Film cutting blade 17 cuts the stopped film. FIG. 5 shows that after the film is cut, fly bar 8 and first conveyor 9 start to move to wrap the article. Fly bar 8 pushes the film through a slot between the first and second conveyers. Feed roller 5 pushes a flap on the first conveyor 9 and stops. The feed rollers 5 wait for another article to be place on the flap 10 to repeat the wrapping cycle for another article.

The predetermined length can be established by relying on a timer or an encoder or a sensing mark to indicate the length of material needed to wrap the article. This is usually done by controlling the final position of the fly bar 8 before stopping fly bar 8. 

1. An apparatus for film wrapping an article comprising means for pushing a flap of the film onto a first conveyor, a second conveyor, means for placing an article on the flap, means for picking up the film from behind the article and moving the film over the article, means for stopping the movement of the film over the article when a predetermined length has been pulled, means for cutting the predetermined length of film needed to wrap said article after the film has stopped, means for continuing the movement of the film over the article whereby the film is pushed into slot, between the first conveyor and the second conveyor, and means for heat shrinking the film around the article.
 2. An apparatus according to claim 1 wherein the means for pushing a flap of the film onto a first conveyor are feed rollers
 3. An apparatus according to claim 1 where in the means for picking up the film from behind the article and moving the film over the article is a fly bar
 4. An apparatus according to claim 1 wherein the means for stopping the movement of the film includes means for stopping the feed roller, flybar and first conveyor
 5. An apparatus according to claim 1 including means for overlapping the film around the article by transferring the article from the first conveyor to the second conveyor.
 6. A process for film wrapping an article comprising pushing a flap of the film onto a first conveyor, positioning a second conveyor next to the first conveyor to form a slot, placing an article on the flap, picking up the film from behind the article and moving the film over the article, stopping the movement of the film over the article, cutting the stopped film to providing a predetermined length of film needed to wrap said article continuing the movement of the film over the article and into the slot between the first conveyor and the second conveyor, and heat shrinking the film
 7. A process according to claim 6 wherein the film is overlapped by transferring the article form the first conveyor to the second conveyor.
 8. A process according to claim 6 where the film is picked up by a flybar.
 9. . A process according to claim 8 wherein the first conveyor and flybar and feed rollers are stopped to prevent the movement of the film.
 10. A process according to claim 8 wherein the first conveyor and the fly bar start moving to continue the movement of the stopped film. 